Study On Vibration Analysis And Structure Improvement Of Hydraulic Turbine Head Cover In Longkaikou Hydropower Station

Francis turbine is currently the world’s most widely used hydraulic turbine type,with the increase of capacity of hydropower generating unit,the stable operation of power grids is becoming more and more big,the influence of the hydroelectric generating set in the process of work,as a result of hydraulic,mechanical,electromagnetic factors will cause varying degrees of vibration,serious when may endanger the safe operation of the power plant and power grid stability.In view of the fact that the top of the turbine in longkaikou power station has a large vibration,the top of the unit in the 0-210 MW load section under the test head has a strong vibration,and the amplitude of horizontal and vertical vibration is more than 400 microns.In order to solve the problems encountered in production practice,the following aspects are studied.Paper first analyzed the dragon mouth power station turbine roof slants big vibration,through the study of the stability test of hydroelectric generating set,vibration test and analysis of top cover,tail water pressure pulsation and other data,analysis and research show that the vibration of the roof stiffness is not influence the top value,the main reasons for the large hydraulic vibration and vibration is larger also have certain relevance.Secondly,in order to solve the problem of large vibration of the top of the hydraulic turbine in longkaikou power station,ANSYS finite element software was used to analyze and study the stiffness,strength and natural frequency of the top cover,and the structure of the top cover was modified and designed to increase the stiffness strength of the top cover.Meanwhile,other auxiliary measures affecting the top cover were also studied.Through the observation and improvement of the prototype test,a complete set of comprehensive control and optimization scheme for reducing the vibration of the head cover was developed,including the improvement of the new cover structure,the improvement of the reinforced structure of the head cover,the improvement of the supplementary air pipe and the optimization of the pretightening torque of the head cover bolt,etc.To further after verification by physical modification effect,the stability test of hydro-generator units again,through test and analysis,the unit to take the new roof structure improvement and the improvement of the top reinforcement structure measures after the effect is good,effectively reduced the top horizontal and vertical vibration value,has provided the safeguard for the safe and stable operation of hydroelectric generating set,the similar of the roof structure design of the turbine and large vibration reduction measures have good reference value.